Owners of any Smart Fortwo models or trim levels such as the coupe hatchback, cabriolet or "cabrio", electric, pure, passion, forfour, prime and proxy may also find these DIY instructions to be helpful.

The OEM 12V battery was Smart part number A-000-982-78-08 or A0009827808.

A compatible replacement "Group Size" H5 12 volt battery is  Bosch # H5-650B or the Everstart MAXX-H5 at Walmart.

The tools needed to remove and replace the battery include a flathead screwdriver, a 10mm socket and a 1/4" drive ratchet.

The first step is to remove the floor mat and set it aside in a safe place.

Then use a flathead screwdriver to rotate the carpet holder plastic fastener in the counterclockwise direction.

Pull off the plastic fastener and set it aside.

Remove the large foam block that contains the flat tire sealant kit and air compressor.

First loosen the negative terminal (located closer to the rear of the car) by turning the nut counterclockwise with the 10mm socket and a 1/4" drive ratchet.

Pull the negative terminal straight off the "-" battery post.

Wrap the terminal with a small towel and tuck it on the side of the battery to help prevent accidental electrical contact.

Loosen the positive terminal by turning the 10mm nut in the counterclockwise direction.

Pull the positive terminal off the "+" battery post.

Loosen the nut by turning it counterclockwise with the 10mm socket and a 1/4" drive ratchet.

Set the 10mm nut aside in a safe place.

Lift the battery hold down clamp up and remove the hook on the left end from its corresponding slot.

Pull the small plastic exhaust gas vent tube on the rear edge of the battery out of its port.

Carefully lift the old battery out of the vehicle and gently set it down on the ground.

Try to avoid dropping or tipping over the old battery to prevent from having battery acid leak out.

A compatible replacement Group Size H5 battery is the Bosch # H5-650B.

Push the positive terminal on to the "+" battery post.

Tighten the 10mm nut in the clockwise direction until it is snug.

Try to avoid over tightening the terminal nut to prevent from damaging the battery post which could lead to an acid leak.

Push the negative terminal on to the "-" battery post.

Tighten the 10mm nut on the negative terminal in the clockwise direction until it is snug.

Re-attach the metal hook at the left end of the hold down bar in to the slot on the left side of the battery housing.

Lower the hold down clamp over the top of the battery.

Tighten the nut in the clockwise direction until it is snug.

Push the plastic gas exhaust vent tube in to the hole on the rear edge of the battery.

Push in the plastic fastener to secure the floor liner in place.

Replace the floor mat.

To test the new 12V battery, start the engine and turn on the headlights.

Please be sure to adjust the time on the clock and program your favorite radio station presets before you start driving.

For more, check out all of my 2008-2014 Smart Fortwo DIY Repair & Maintenance Guides.